Watchtower, It has nothing to do with parents. What it comes down to is introspection and exposure. People in their 20's and especially 30's start thinking. After 20-30 years in the truth, there has been an accumulative exposure to people in the field and at work who are knowledgeable about evolution and inconsistencies in creationism. They learn from "non-apostates" the lies and contradictions percolating in the organization. They realize that none of what they have been taught as truth makes any sense. They release that they will have to retire and die in the real world, so they have to actually live in the real world and get a full-time job etc.
There comes a point in life when the scales fall off and you realize that you are slaving for a human organization that wants all of your time, money and energy before you die. Therefore, young ones everywhere are dropping the microphone and exiting stage left. You can hear the jingle as the shackles of Fear, Obligation and Guilt slide off their ankles at the door.